EP1808314B1 - Run-flat-reifen - Google Patents

Run-flat-reifen Download PDF

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Publication number
EP1808314B1
EP1808314B1 EP05783386A EP05783386A EP1808314B1 EP 1808314 B1 EP1808314 B1 EP 1808314B1 EP 05783386 A EP05783386 A EP 05783386A EP 05783386 A EP05783386 A EP 05783386A EP 1808314 B1 EP1808314 B1 EP 1808314B1
Authority
EP
European Patent Office
Prior art keywords
tire
section
rim
bead
run
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
EP05783386A
Other languages
English (en)
French (fr)
Other versions
EP1808314A1 (de
EP1808314A4 (de
Inventor
Masahiro c/o TOYO TIRE & RUBBER CO. LTD. SEGAWA
Kazuhiko c/o TOYO TIRE & RUBBER CO. LTD. KAWAMURA
Jun c/o TOYO TIRE & RUBBER CO. LTD. KODAMA
Masayuki c/o TOYO TIRE & RUBBER CO. LTD. KANAI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyo Tire Corp
Original Assignee
Toyo Tire and Rubber Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2004279758A external-priority patent/JP4399848B2/ja
Priority claimed from JP2004319370A external-priority patent/JP4399850B2/ja
Application filed by Toyo Tire and Rubber Co Ltd filed Critical Toyo Tire and Rubber Co Ltd
Publication of EP1808314A1 publication Critical patent/EP1808314A1/de
Publication of EP1808314A4 publication Critical patent/EP1808314A4/de
Application granted granted Critical
Publication of EP1808314B1 publication Critical patent/EP1808314B1/de
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
    • B60C15/06—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C13/00—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof
    • B60C13/009—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof comprising additional bead cores in the sidewall
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C13/00—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof
    • B60C13/04—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof having annular inlays or covers, e.g. white sidewalls
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
    • B60C15/02—Seating or securing beads on rims
    • B60C15/024—Bead contour, e.g. lips, grooves, or ribs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C17/00—Tyres characterised by means enabling restricted operation in damaged or deflated condition; Accessories therefor
    • B60C17/0009—Tyres characterised by means enabling restricted operation in damaged or deflated condition; Accessories therefor comprising sidewall rubber inserts, e.g. crescent shaped inserts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T152/00—Resilient tires and wheels
    • Y10T152/10—Tires, resilient
    • Y10T152/10495—Pneumatic tire or inner tube
    • Y10T152/10819—Characterized by the structure of the bead portion of the tire
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T152/00—Resilient tires and wheels
    • Y10T152/10—Tires, resilient
    • Y10T152/10495—Pneumatic tire or inner tube
    • Y10T152/10819—Characterized by the structure of the bead portion of the tire
    • Y10T152/10846—Bead characterized by the chemical composition and or physical properties of elastomers or the like

Definitions

  • the present invention relates to a so-called double bead type run flat tire provided with a reinforcing rubber layer arranged in a side wall section, an annular protrusion section protruding to an outer side in a tire width direction of a bead section, and a bead arranged in the annular protrusion section.
  • the reinforcing rubber layer supports a tire so as to suppress a flattening at a time when an air pressure in an inner section of the tire is lowered due to a puncture or the like, whereby a run-flat traveling can be executed.
  • a pressure application to a rim of a bead section is weakened and a fitting force is lowered in a state in which the air pressure in the inner section of the tire is lowered (in a run-flat state)
  • a run-flat tire provided with an annular protrusion section in an outer side in a tire width direction of a bead section.
  • an annular protrusion section 10 shown in Fig. 8(a) has a smaller inner diameter than an outer diameter of a rim flange while protruding to an outer side of the rim flange of a rim 8, it is possible to improve a rim disengagement resistance while holding the rim flange at a time of a run-flat traveling.
  • the run-flat tire mentioned above it has been known that the rim disengagement resistance is not sufficient. In other words, as shown in Fig.
  • a so-called double bead type run-flat tire provided with an annular protrusion section 10 protruding to an outer side in a tire width direction of a bead section 1, and a second bead 1b arranged in the annular protrusion section 10.
  • the annular protrusion section 10 reinforced by the second bead 1b can firmly hold a rim flange 8a at a time of a run-flat traveling, it is possible to effectively prevent the rim disengagement.
  • the run-flat tire mentioned above is disclosed, for example, in the following Patent Documents 1 to 3.
  • the conventional double bead type run-flat tire there is a case that the rim disengagement resistance is not sufficient, and the conventional double bead type run-flat tire can not respond to a demand of intending to securely prevent the rim disengagement.
  • Conventionally, in order to improve the rim disengagement resistance there have been employed means for increasing a volume of the reinforcing rubber layer or increasing a tread rigidity, however, there has been a problem that a deterioration of ride comfort performance and an increase of a tire weight are caused.
  • Fig. 10 is a cross sectional view of a main section showing a bead section of a conventional double bead type run-flat tire.
  • a graph of a fitting pressure applied to a rim base 8b at a time of grounding in the run-flat traveling As shown in Fig. 10 , it has been known that a fitting pressure of a bead toe 1t is comparatively low at a time of the run-flat traveling, in the conventional run-flat tire. Further, the inventors of the present invention have found that the reduction of the fitting pressure of the bead toe 1t lowers a fitting force to a rim 8, and deteriorates the rim disengagement resistance.
  • Patent Document 5 Japanese Patent Application Laid-open No. S51-116 507
  • Patent Document 2 Japanese Patent Application Laid-open No. S52-121 204
  • Patent Document 3 Japanese Patent Application Laid-open No. S53-138
  • Patent Document 4 Japanese Patent Application Laid-open No. 2000-006 621
  • Patent Document 5 Japanese Patent Application Laid-open No. H11-157 311 .
  • the present invention is made by taking the actual conditions mentioned above into consideration, and an object of the present invention is to provide a so-called double bead type run-flat tire which can achieve both of a rim disengagement resistance and a rim assembling property.
  • the present invention provides a run-flat tire comprising: a pair of bead sections each having an annular first bead; side wall sections respectively extending to a tire outer peripheral side from the bead sections; a reinforcing rubber layer arranged in the side wall section so as to be formed in a crescent cross sectional shape; an annular protrusion section protruding to an outer side in a tire width direction from at least one of the bead sections, and having an inner peripheral side surface facing to an outer peripheral side curved surface of a rim flange at a time of installing a specified rim; and an annular second bead arranged in the annular protrusion section, wherein the run-flat tire comprises: a ridge section connecting to an outer side in the tire width direction from an inner peripheral side surface of the annular protrusion section so as to protrude to an inner peripheral side of the tire, and having an inner diameter smaller than an outer diameter of the rim flange
  • the annular protrusion section reinforced by the second bead can hold the rim flange at a time of the run-flat traveling, an installation stability to the rim is increased, and it is possible to achieve an excellent rim disengagement resistance. Further, in accordance with the run-flat tire of the present invention, since the first soft rubber layer having the corner section tapered toward the tire inner peripheral side is arranged in the protrusion section having the inner diameter smaller than the outer diameter of the rim flange, the protrusion section tends to be bent to the inner side in the tire width direction and the rim assembling property can be improved.
  • the specified rim indicates the rim forming the standard determined by JATMA in correspondence to the tire size
  • the specified rim installing time indicates a state of being installed to the specified rim at an air pressure of 180 kPa.
  • the first soft rubber layer means a softer rubber layer than the other rubber layers arranged in the protrusion section.
  • the first soft rubber layer is formed in a triangular cross sectional shape, and a median line passing through an apex of the corner section is inclined to an inner side in the tire width direction toward the tire inner peripheral side.
  • the shape in which the corner section of the first soft rubber layer is inclined to the inner side in the tire width direction while being tapered toward the inner peripheral side of the tire Accordingly, the protrusion section is more easily bent to the inner side in the tire width direction, and it is possible to more easily execute the work of pulling up the annular protrusion section so as to get over the flange. Further, since the first soft rubber layer is formed in the triangular cross sectional shape, it is possible to achieve the operations and effects mentioned above on the basis of the simple shape, while obtaining the shape which is easily arranged in the protrusion section.
  • a hardness in accordance with JISK6253 durometer hardness test is between 60 degree and 70 degree.
  • the hardness of the first soft rubber layer is set to the range mentioned above, it is possible to secure an effect of improving the rim disengagement resistance by the annular protrusion section while lowering the hardness of the protrusion section so as to improve the rim assembling property.
  • the run-flat tire is provided with a projection section formed in an inner side in the tire width direction of the ridge section, and arranged in the tire inner peripheral side from a leading end of the rim flange at a time of installing a specified rim.
  • the projection section formed in the inner side in the tire width direction of the ridge section is engaged with the rim flange so as to prevent the annular protrusion section from moving away from the rim flange, thereby effectively improving the rim disengagement resistance. Further, since the projection section is formed in the inner side in the tire width direction of the ridge section, it is possible to effectively achieve both the rim disengagement resistance and the rim assembling property without resisting the work of pulling up the annular protrusion section so as to get over the rim flange at a time of assembling the rim.
  • results shown by a graph in Fig. 11 are obtained by researching a displacement of the annular protrusion section in accordance with a tire rolling in the run-flat traveling.
  • a horizontal axis of the graph corresponds to an angle of rotation of the tire corresponding to Fig. 12 , and a range of 45 degree is set to each of a knock-over side and a boot-out side with respect to a ground center point in a circumferential direction.
  • a vertical axis corresponds to a displacement to the inner side in the tire diametrical direction of the annular protrusion section.
  • the annular protrusion section is displaced to the inner side in the tire diametrical direction, in the knock-over side at a time of the tire rolling.
  • the run-flat tire in accordance with the present invention is preferably structured such that in the structure mentioned above, the inner peripheral side surface of the annular protrusion section is provided with a second soft rubber layer arranged near a contact point of a tangential line capable of being drawn from an intersecting point between a straight line drawn from a center of the first bead to an inner side in the tire diametrical direction and an outer peripheral side surface of the rim base, to an outer peripheral side curved surface of the rim flange at a time of installing a specified rim.
  • the annular protrusion section having the second bead is displaced to the inner side in the tire diametrical direction while the side wall section generates the bending deformation, at the run-flat traveling time, the moment having the supporting point in the region which is in contact with the rim flange is generated.
  • the moment has a remarkable effect of lowering the fitting pressure of the bead toe in the case of setting the contact point of the tangential line capable of being drawn from the intersecting point between the straight line extending to the inner side in the tire diametrical direction from the center of the first bead and the outer peripheral side surface of the rim base, to the outer peripheral side curved surface of the rim flange, to the supporting point.
  • the second soft rubber layer corresponds to a softer rubber layer than the other rubber layers arranged in the inner peripheral side surface of the annular protrusion section.
  • the run-flat tire described in the Patent Document 5 mentioned above is not the so-called double bead type run-flat tire, but is structured such that the rim deflection preventing layer is arranged in the section facing to the rim flange upper section, and can not achieve the excellent rim disengagement resistance by dispersing the moment mentioned above.
  • a run-flat tire as claimed in claim 5 wherein in the case of setting a point facing to the contact point in the inner peripheral side surface of the annular protrusion section to a reference point, a distance from the reference point to a center of the first bead in the tire width direction to L1, a distance from the reference point to a center of the second bead in the tire width direction to L2, a distance from the reference point to an inner end in the tire width direction of the inner peripheral side surface of the second soft rubber layer to a, and a distance from the reference point to an outer end in the tire width direction of the inner peripheral side surface of the second soft rubber layer to b , the run-flat tire satisfies a relation 0.2L1 ⁇ a ⁇ 0.5L1 and 0.3L2 ⁇ b ⁇ 0.8L2.
  • the point facing to the contact point indicates an intersecting point between a normal line drawn from the contact point and the inner peripheral side surface of the annular protrusion section.
  • a hardness in accordance with JISK6253 durometer hardness test is between 50 degree and 65 degree.
  • a fiber layer is arranged between the second bead and the second soft rubber layer.
  • annular protrusion section reinforced by the second bead and the fiber layer is pressed to the outer peripheral side curved surface of the rim flange at the run-flat traveling time, by arranging the fiber layer between the second bead and the second soft rubber layer, it is possible to effectively increase the fitting force to the rim, and it is possible to achieve the more excellent rim disengagement resistance.
  • Fig. 1 is a half cross sectional view showing an example of a run-flat tire in accordance with a first embodiment of the present invention installed to a specified rim.
  • Fig. 2 is a cross sectional view of a main section schematically showing a bead section of the run-flat tire shown in Fig. 1 .
  • the run-flat tire is provided with a pair of annular bead sections 1, side wall sections 2 respectively extending to tire outer peripheral sides from the bead sections 1, and a tread section 4 connecting the respective outer peripheral side ends of the side walls 2 to each other via a shoulder section, as shown in Fig. 1 .
  • a bead 1a (corresponding to the first bead) in which a converged body of bead wires, for example, constituted by a steel wire is formed in an annular shape in a tire peripheral direction is arranged in the bead section 1, and a bead filler 12 is arranged in an outer periphery of the tire.
  • the bead section 1 is arranged in the tire outer periphery of a rim base 8a of a rim 8, and is pressed by the rim flange 8a if a normal air pressure exists, whereby the tire is fitted to the rim 8.
  • a carcass layer 20 is constituted by a carcass ply 14 structured, for example, such that a polyester cord is arranged at approximately 90 degree with respect to a tire equator line TC, and is arranged in such a manner as to be bridged between a pair of bead sections 1.
  • the carcass ply 14 is wound up to an outer side in a tire width direction in such a manner as to pinch the bead 1a and the bead filler 12.
  • a reinforcing rubber layer 9 in which a tire meridian cross section is formed in approximately a crescent shape is arranged in an inner side of the carcass layer 20 of the side wall section 2. Accordingly, when an air pressure in the inner section of the tire is lowered, a bending deformation of the tire is suppressed, and a run-flat traveling can be executed.
  • the reinforcing rubber layer 9 is constituted, for example, by a rubber layer in which a rubber hardness (a rubber hardness measured in accordance with JISK6253 type A durometer hardness test) is between 65 degree and 90 degree.
  • the reinforcing rubber layer 9 provided in the run-flat tire in accordance with the present invention can adopt any reinforcing rubber layer without being specifically limited by a thickness, a hardness or the like, as far as the reinforcing rubber layer is used in a conventional side reinforcing type run-flat tire.
  • the reinforcing rubber layer 9 is not limited to the structure constituted by a single rubber layer, but may be structured by a plurality of rubber layers having different physical properties such as hardness or the like.
  • An inner liner layer 5 for holding the air pressure is arranged in an inner peripheral side of the carcass layer 20. Further, a belt layer 6 and a belt reinforcing layer 7 for reinforcing on the basis of a hoop effect are arranged in an outer peripheral side of the carcass layer 20.
  • the belt layer 6 is constituted by two belt plies each structured, for example, such that a steel cord is arranged at an angle of about 25 degree with respect to the tire equator line TC, and is layered in such a manner that the steel cords intersect in inverted directions between the belt plies.
  • an organic fiber such as a rayon, a nylon, an aramid or the like is used in addition to the cords mentioned above.
  • a surface treatment, an adhesion treatment or the like is applied to the cords.
  • the structure described above is the same structure as that of the general side reinforcing type run-flat tire, and the present invention can be applied to any run-flat tire having the structure mentioned above.
  • raw material rubbers for the rubber layer and the like are natural rubber, styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), butyl rubber (IIR) and the like. These rubbers are reinforced using filler such as carbon black and silica, and cure, accelerator, plasticizer, antioxidant or the like is appropriately mixed.
  • annular protrusion section 10 is formed in an outer side in a tire width direction of the bead section 1.
  • the annular protrusion section 10 in the present embodiment protrudes to an outer side in the tire width direction from the rim flange 8a, and has an inner peripheral side surface 11 facing thereto along an outer peripheral side curved surface of the rim flange 8a.
  • the annular protrusion section 10 is formed in each of the bead sections 1 in both sides, however, it is preferable that the annular protrusion section 10 is formed at least in one bead section 1, and can be formed, for example, only in an outer side of a vehicle at a time of being installed.
  • the bead 1b (corresponding to the second bead) in which the bead wire is formed in an annular shape in the tire peripheral direction is arranged in the annular protrusion section 10.
  • the bead 1b in accordance with the present embodiment is arranged in such a manner that a center position is positioned in a tire outer peripheral side from an outermost diameter point of the rim flange 8a and in an outer side in the tire width direction.
  • the bead 1b is not limited to the structure constituted by the converged body of the same bead wires as those of the bead 1a, but may be constituted, for example, by a converged body of organic fibers or a rubber bead made of a fiber reinforcing rubber.
  • the ridge section 23 is connected to the outer side in the tire width direction from the inner peripheral side surface 11 of the annular protrusion section 10, and is formed in such a manner as to rise up to a tire inner peripheral side.
  • the ridge section 23 is formed in an annular shape, and has an inner diameter smaller than an outer diameter of the rim flange 8a.
  • the inner diameter of the ridge section 23 is exemplified by an inner diameter 4.0 mm to 14.0 mm smaller than an outer diameter of the rim flange 8a.
  • an outer diameter of the rim flange 8a indicates a diameter in the outermost diameter point of the rim flange 8a. Since the annular protrusion section 10 has the ridge section 23, the annular protrusion section 10 effectively holds the rim flange 8a at the run-flat traveling time, whereby it is possible to improve a rim disengagement resistance.
  • a soft rubber layer 15 (corresponding to the first soft rubber layer) is arranged annularly in the ridge section 23, and is structured by the softer rubber layer than the other rubber layer 17 constituting the ridge section 23.
  • a rubber hardness of the rubber layer 17 is, for example, between 73 degree and 80 degree, and it is preferable that the soft rubber layer 15 has a rubber hardness lower than that of the rubber layer 17 by 5 degree or more.
  • the soft rubber layer 15 has a corner section 16 tapered toward the tire inner peripheral side, and is arranged in the tire inner peripheral side of the bead 1b in such a manner that a tire meridian cross section is formed in a triangular shape. Accordingly, the ridge section tends to bend to an inner side in the tire width direction at a time of assembling the rim, and it is possible to easily execute a work of pulling up the annular protrusion section 10 to the outer side so as to get over the rim flange 8a.
  • the rubber hardness of the soft rubber layer 15 is preferably between 60 degree and 70 degree, and more preferably between 65 degree and 70 degree. If the rubber hardness of the soft rubber layer 15 is less than 60 degree, there is a tendency that the hardness of the ridge section 23 is excessively lowered, and the rim disengagement resistance is lowered. On the other hand, if the rubber hardness becomes more than 75 degree, the ridge section 23 is hard to bend to the inner side in the tire width direction, and there is a tendency that an effect of improving the rim assembling property becomes small.
  • the soft rubber layer 15 is preferably arranged such that the tire meridian cross section is formed in the triangular shape as in the present embodiment, and is more preferably structured, as shown in Fig. 2 , such that a median line 15a passing through an apex of the corner section 16 tapered toward the tire inner peripheral side is inclined to the inner side in the tire width direction toward the tire inner peripheral side.
  • the median line indicates a segment connecting an apex of a triangle and a median point of an opposite side facing to the apex.
  • the tire meridian cross section of the soft rubber layer 15 is formed in a triangular shape in which the corner section 16 is inclined to the inner side in the tire width direction while being tapered toward the tire inner peripheral side, and the ridge section 23 tends to bend to the inner side in the tire width direction so as to improve the rim assembling property.
  • a dimension of the soft rubber layer 15 can be appropriately set in correspondence to the dimension of the ridge section 23, however, a thickness (a dimension in a tire diametrical direction) of the soft rubber layer 15 is preferably between 1.5 mm and 5.0 mm, and more preferably between 2.0 mm and 3.5 mm. If the thickness is less than 1.5 mm, there is a tendency that an effect of bending the ridge section 23 by the soft rubber layer 15 becomes small. On the other hand, if it becomes more than 5.0 mm, the hardness of the ridge section 23 is excessively lowered, and there is a tendency that the rim disengagement resistance is lowered.
  • a projection section 18 protruding to an inner side in the tire width direction is formed in the ridge section 23 in accordance with the present embodiment.
  • the projection section 18 is arranged in the tire inner peripheral side from the leading end of the rim flange 8a, whereby the projection section 18 is engaged with the rim flange 8a at a time when the bead section 1 is going to detach from the rim 8, and it is possible to effectively improve the rim disengagement resistance. Since the projection section 18 mentioned above is formed in the inner side in the tire width direction of the ridge section 23, the projection section 18 does not obstruct a work of pulling up the annular protrusion section 10 to the outer side so as to get over the rim flange 8a.
  • a dimension of the projection section 18 can be appropriately set, however, it is preferable that a protruding amount A based on the inner side surface in the tire width direction of the protrusion section 23 is between 1.0 mm and 2.5 mm. In the case that the protruding amount A is more than 2.5 mm, the projection section 18 excessively protrudes to the inner side in the tire width direction, and there is a tendency that it is hard to arrange the projection section 18 in the tire inner peripheral side from the leading end of the rim flange 8a at time of assembling the rim.
  • the protruding amount A is less than 1.0 mm, the protruding amount of the projection section 18 is too small, and there is a tendency that an effect of engaging with the rim flange 8a so as to suppress the rim disengagement becomes small.
  • the inner surface in the tire width direction of the ridge section 23 indicates a surface which is connected from the inner peripheral side surface 11 of the annular protrusion section 10 and is positioned in the outermost side in the tire width direction.
  • Each of test tires installed to a rim having a wheel size of 18 x 8JJ is attached to a left front side of an actual car (domestically built 3000 cc class FR car), and there is executed a so-called J-turn travel of turning on a circular course having a radius of 20 m in a clockwise direction from a straight traveling.
  • Each of the test tires is set to a run flat state having an internal pressure of 0 kPa, and a rim disengagement resistance is evaluated on the basis of a traveling speed (which is in proportion to a lateral G) at a time when the rim disengagement is generated.
  • the traveling speed starts from 25 km/h, and the travel is executed until the rim disengagement is generated in accordance with a method of 5 km/h increment.
  • An evaluation is executed by an index number in which the Conventional Example 1 is set to 100. The larger the numerical value is, the higher the traveling speed at a time when the rim disengagement is generated is, that is, the more excellent the rim disengagement resistance is.
  • a rim assembling property is evaluated by measuring a working time required for assembling each of the test tires to the rim.
  • the evaluation is executed on the basis of an index number in which a Conventional Example 1 is set to 100.
  • a conventional double bead type run-flat tire (tire size 245/40ZR18) is manufactured so as to be provided with no soft rubber layer 15 and no projection section 18, and is set to a Conventional Example 1.
  • the run-flat tire is manufactured in the same manner as the Conventional Example except a point that the soft rubber layer 15 shown in Fig. 1 is provided, and is set to Examples 1 and 2. Further, the run-flat tire is manufactured in the same manner as the Example 1 except a point that the projection section 18 as shown in Fig. 1 is provided, and is set to an Example 3. In this case, a protruding amount A of the projection section 18 is set to 1.5 mm.
  • the run-flat tire is manufactured in the same manner as the Example 1 except a point that the hardness of the soft rubber layer 15 is set to that of the other rubber layer 17 arranged in the ridge section 23, and is set to a Comparative Example.
  • Table 1 Conventional Example 1 Example 1 Example 2 Example 3 Comparative Example Hardness of rubber layer 17 75 75 75 75 75 75 Hardness of soft rubber layer 15 - 67 60 67 75 Rim disengagement resistance 100 100 95 120 100 Rim assembling property 100 120 130 120 100
  • Fig. 5 is a cross sectional view of a tire meridian showing an example of a run-flat tire in accordance with a second embodiment of the present invention at a time of attaching a specified rim.
  • Fig. 6 is a cross sectional view of a main section of a bead section at a time of attaching the specified rim to the run-flat tire. Since the second embodiment has approximately the same structure and operation as those of the first embodiment except a point that the inner peripheral side surface 11 of the annular protrusion section 10 has the following structure, the same reference numerals are attached to the same members and positions as the members and the positions described in the first embodiment, and an overlapping description will be omitted. Further, in the drawings referred in the second embodiment, the description of the soft rubber layer 15 arranged in the ridge section 13 will be omitted.
  • the inner peripheral side surface 11 of the annular protrusion section 10 is away little by little along the outer peripheral side curved surface of the rim flange 8a, and is smoothly connected to the side wall section 2 from the outer peripheral side.
  • the annular protrusion section 10 is not limited to the shape shown in the present embodiment, but may be structured, for example, such that the tire meridian cross section is formed in a semicircular shape, a trapezoidal shape or the like, or may be structured such as to largely protrude to the outer side in the tire width direction so as to be capable of holding the rim flange 8a.
  • the soft rubber layer 13 (corresponding to the second soft rubber layer) softer than the other rubber layer 22 arranged in the inner peripheral side surface 11 is arranged in the inner peripheral side surface 11 of the annular protrusion section 10. It is preferable that the soft rubber layer 13 is softer in the rubber hardness than the other rubber layer 22 by 5 degree or more.
  • the rubber hardness of the soft rubber layer 13 is preferably between 50 degree and 65 degree, and more preferably between 55 degree and 60 degree. If the rubber hardness of the soft rubber layer 13 is less than 50 degree, the attrition caused by the contact with the rim flange 8a tends to be generated. On the other hand, if it becomes more than 65 degree, the effect of dispersing the moment having the supporting point in the soft rubber layer 13 tends to become smaller, and the effect of improving the rim disengagement resistance tends to become smaller.
  • the soft rubber layer 13 is arranged in a region near a contact point P of a tangential line T which can be drawn from an intersecting point C between a straight line S extending to an inner side in the tire diametrical direction from a center of the bead 1 a and an outer peripheral side surface of the rim base 8b, to the outer peripheral side curved surface of the rim flange 8a.
  • the moment generated at the run-flat traveling time remarkably has an effect of lowering the fitting pressure of the bead toe at a time of setting the contact point P to the supporting point, however, it is possible to disperse the moment so as to improve the rim disengagement resistance by arranging the soft rubber layer 13 in the region near the contact point P.
  • a point facing to the contact point P in the inner peripheral side surface 11 of the annular protrusion section 10 is set to a reference point P'.
  • the reference point P' corresponds to an intersecting point between a normal line drawn from the contact point P and the inner peripheral side surface 11 of the annular protrusion section 10. It is preferable that the soft rubber layer 13 is arranged in a region in which the reference point P' is set at approximately the center, as shown in Fig. 6 .
  • a thickness t of the soft rubber layer 13 on the basis of the inner peripheral side surface 11 is preferably equal to or more than 1.5 mm, and more preferably between 1.8 mm and 2.5 mm. If the thickness t is less than 1.5 mm, the soft rubber layer 13 is too thin, and there is a tendency that the effect of dispersing the moment becomes small. Further, in the present embodiment, there is shown the example in which the soft rubber layer 13 is formed in the approximately crescent shape in the tire meridian cross section, however, the present invention is not limited to this, but may be formed, for example, in a sheet shape, a semicircular shape, a trapezoidal shape or the like.
  • a fiber layer 26 is arranged between the bead 1b and the soft rubber layer 13. Accordingly, it is possible to effectively increase the fitting force to the rim 8 at the run-flat traveling time so as to achieve a more excellent rim disengagement resistance.
  • the fiber layer 26 there are exemplified a steel cord, or a chafer constituted by an organic fiber such as a rayon, a nylon, a polyester, an aramid or the like.
  • Fig. 7 is a cross sectional view of a main section of a bead section positioned in a road surface side in the run-flat traveling after the air pressure in the inner section of the tire is lowered from a state shown in Fig. 6 .
  • the annular protrusion section 10 having the bead 1b is displaced in the inner side in the tire diametrical direction while the side wall section 2 generates the bending deformation.
  • the present invention is not limited to this, but may be structured such that the inner peripheral side surface 11 of the annular protrusion section 10 is brought into contact with the rim flange 8a at the contact point P at a time of attaching the specified rim.
  • the soft rubber layer 13 may not necessarily brought into tight contact with the rim flange 8a at the run-flat traveling time, as far as the soft rubber layer 13 is arranged near the contact point P .
  • a rim disengagement resistance is evaluated on the basis of the J-turn traveling mentioned above. An evaluation is executed by an index number in which a Conventional Example 2 is set to 100. The larger the numerical value is, the higher the traveling speed at a time when the rim disengagement is generated is, that is, the rim disengagement resistance is excellent.
  • a test time until a problem such as failure caused by a crack, a separation or an attrition is recognized in the bead section is measured by traveling on a drum having a diameter of 1700 mm under a condition of an air pressure of 0 kPa, a speed of 80 km/h and an application of JATMA65 % load, on the basis of a method in accordance with ISO draft.
  • An evaluation is executed by an index number in which a Conventional Example 2 is set to 100. The higher the numerical value is, the longer the test time is, that is, the bead durability is excellent.
  • test tire having a structure shown in Figs. 5 and 6 and a tire size of 225/45ZR17.
  • the Conventional Example 2 is structured such that the soft rubber layer 13 is not provided, and only the rubber layer 22 is arranged in the inner peripheral side surface 11 of the annular protrusion section 10.
  • dimensions ( L, a, b and t ) of the soft rubber layer 13, and hardness of the rubber layer 22 and the soft rubber layer 13 are respectively set to values shown in Table 2.
  • the test is executed by attaching each of the test tires to the rim having the wheel size of 17 ⁇ 7.5-JJ, at a time of evaluating the items mentioned above. The results are shown in Table 2.
  • Example 10 Distance L1 (mm) - 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Distance L2 (mm) - 8 8 8 8 8 8 8 8 8 8 1 11 8 Distance b (mm) - 3 6 6 6 5 8 6 Thickness 1 (mm) - 1.6 1.8 1.8 1.8 1.8 1.8 1.2 Hardness of rubber layer 22 71 71 71 71 71 71 Hardness of soft rubber layer 13 - 58 58 48 68 58 58 58 Rim disengagement resistance 100 106 109 112 101 101 101 114 101 Bead durability 100 100 100 92 100 100 85 100
  • each of the Examples of the present invention can disperse the moment of lifting up the bead section by setting the soft rubber layer in the inner peripheral side surface of the annular protrusion section, and is excellent in the rim disengagement resistance in comparison with the Conventional Example.
  • the soft rubber layer is too soft in the Example 6, and the dimension of the soft rubber layer is too larger in the Example 9, the attrition tends to be generated in the inner peripheral side surface of the annular protrusion section due to the contact with the rim flange, and there is a tendency that the bead durability becomes comparatively low.
  • the soft rubber layer is too hard in the Example 7, and the dimension of the soft rubber layer is too small in the Examples 8 and 10, there is a tendency that the moment dispersing effect becomes small, and the rim disengagement resistance improving effect becomes small.
  • the rim disengagement resistance can be largely improved while securing the bead durability, and it is known that it is preferable to set each of the dimensions ( L, a, b and t ) and the hardness of the soft rubber layer to the range mentioned above.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Tires In General (AREA)

Claims (8)

  1. Notlaufreifen, der folgendes aufweist:
    - ein Paar Wulstbereiche (1), von denen jeder einen ringförmigen ersten Wulstkern (1a) aufweist;
    - Seitenwandbereiche (2), die sich von den Wulstbereichen (1) jeweils zu einer Reifenaußenumfangsseite erstrecken;
    - eine Verstärkungsgummischicht (9), die in dem Seitenwandbereich (2) angeordnet und mit einer sichelförmigen Querschnittsgestalt ausgebildet ist;
    - einen ringförmigen Vorsprungbereich (10), der von mindestens einem der Wulstbereiche (1) in Reifenbreitenrichtung zu einer Außenseite vorsteht und eine innenumfangsseitige Fläche (11) aufweist, die zum Zeitpunkt der Montage auf einer bestimmten Felge (8) einer außenumfangsseitigen gekrümmten Fläche eines Felgenhorns (8a) zugewandt gegenüberliegt; und
    - einen ringförmigen zweiten Wulstkern (1b), der in dem ringförmigen Vorsprungbereich (10) angeordnet ist,
    wobei der Notlaufreifen folgendes aufweist:
    - einen Rippenbereich (23), der von einer innenumfangsseitigen Fläche (11) des ringförmigen Vorsprungbereichs (10) in Reifenbreitenrichtung derart an eine Außenseite anschließt, daß er auf eine Innenumfangsseite des Reifens vorsteht, und der einen Innendurchmesser aufweist, der kleiner ist als ein Außendurchmesser des Felgenhorns (8a); und
    - eine erste Weichgummischicht (15), die in dem Rippenbereich (23) angeordnet ist und einen Eckbereich (16) aufweist, der sich in Richtung auf die Reifeninnenumfangsseite verjüngt.
  2. Notlaufreifen nach Anspruch 1,
    wobei die erste Weichgummischicht (15) mit einer dreieckigen Querschnittsform ausgebildet ist und wobei eine Mittellinie (15a), die durch einen Scheitel des Eckbereichs (16) hindurchgeht, in Richtung auf die Reifeninnenumfangsseite zu einer in Reifenbreitenrichtung innen gelegenen Seite geneigt ist.
  3. Notlaufreifen nach Anspruch 1 oder 2,
    wobei ini der ersten Weichgummischicht (15) die Härte gemäß dem JISK6253-Durometer-Härtetest (Typ A) zwischen 60 Grad und 70 Grad liegt.
  4. Notlaufreifen nach einem der Ansprüche 1 bis 3,
    wobei der Notlaufreifen mit einem vorstehenden Bereich (18) versehen ist, der in Reifenbreitenrichtung an einer Innenseite des Rippenbereichs (23) ausgebildet ist und zum Zeitpunkt der Montage auf einer bestimmten Felge (8) von einem vorderen Ende des Felgenhorns (8a) weg auf der Reifeninnenumfangsseite angeordnet ist.
  5. Notlaufreifen nach einem der Ansprüche 1 bis 4,
    wobei die innenumfangsseitige Fläche (11) des ringförmigen Vorsprungbereichs (10) mit einer zweiten Weichgummischicht (13) versehen ist, die zum Zeitpunkt der Montage auf der bestimmten Felge (8) in der Nähe einer Berührungsstelle einer Tangentiallinie angeordnet ist, die sich von einem Schnittpunkt zwischen einer geraden Linie, die von einem Zentrum des ersten Wulstkerns (1a) auf eine Innenseite in Reifendiametralrichtung gezogen wird, und einer außenumfangsseitigen Fläche der Felgenbasis (8b), zu einer außenumfangsseitigen gekrümmten Fläche des Felgenhorns (8a) ziehen läßt.
  6. Notlaufreifen nach Anspruch 5,
    wobei in der zweiten Weichgummischicht (13) die Härte gemäß dem JISK6253-Durometer-Härtetest (Typ A) zwischen 50 Grad und 65 Grad liegt.
  7. Notlaufreifen nach Anspruch 5,
    wobei bei Vorgabe eines der Berührungsstelle (P) auf der innenumfangsseitigen Fläche (11) des ringförmigen Vorsprungbereichs (10) zugewandten Punkts als Referenzpunkt (P'), einer Distanz von dem Referenzpunkt (P') bis zu einem Zentrum des ersten Wulstkerns (1a) in der Reifenbreitenrichtung mit L1, einer Distanz von dem Referenzpunkt (P') bis zu einem Zentrum des zweiten Wulstkerns (1b) in der Reifenbreitenrichtung mit L2, einer Distanz von dem Referenzpunkt (P') bis zu einem in der Reifenbreitenrichtung inneren Ende der innenumfangsseitigen Fläche (11) der zweiten Weichgummischicht (13) mit "a" sowie einer Distanz von dem Referenzpunkt (P') bis zu einem in der Reifenbreitenrichtung äußeren Ende der innenumfangsseitigen Fläche der zweiten Weichgummischicht (13) mit "b", der Notlaufreifen die Relationen 0 , 2 ⁢ L ⁢ 1 ≤ a ≤ 0 , 5 ⁢ L ⁢ 1
    Figure imgb0001
    und 0 , 3 ⁢ L ⁢ 2 ≤ b ≤ 0 , 8 ⁢ L ⁢ 2
    Figure imgb0002
    erfüllt.
  8. Notlaufreifen nach einem der Ansprüche 5 bis 7,
    wobei eine Faserschicht (26) zwischen dem zweiten Wulstkern (1b) und der zweiten Weichgummischicht (13) angeordnet ist.
EP05783386A 2004-09-27 2005-09-14 Run-flat-reifen Expired - Fee Related EP1808314B1 (de)

Applications Claiming Priority (3)

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JP2004279758A JP4399848B2 (ja) 2004-09-27 2004-09-27 ランフラットタイヤ
JP2004319370A JP4399850B2 (ja) 2004-11-02 2004-11-02 ランフラットタイヤ
PCT/JP2005/016950 WO2006035603A1 (ja) 2004-09-27 2005-09-14 ランフラットタイヤ

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EP1808314A1 EP1808314A1 (de) 2007-07-18
EP1808314A4 EP1808314A4 (de) 2008-11-26
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EP (1) EP1808314B1 (de)
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JP5049640B2 (ja) * 2007-05-07 2012-10-17 東洋ゴム工業株式会社 ランフラットタイヤ
DE102008028780A1 (de) * 2008-06-17 2009-12-24 Continental Aktiengesellschaft Fahrzeugluftreifen mit Felgenschutzrippe
FR2947482B1 (fr) * 2009-07-02 2012-05-18 Salomon Sas Pneumatique pour cycle
CN103347708B (zh) 2011-02-04 2015-08-19 株式会社普利司通 充气轮胎用轮辋
JP6377390B2 (ja) * 2014-04-04 2018-08-22 株式会社ブリヂストン ランフラットラジアルタイヤ
DE102022200392A1 (de) 2022-01-14 2023-07-20 Continental Reifen Deutschland Gmbh Fahrzeugluftreifen

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JPS5946801B2 (ja) * 1975-04-02 1984-11-15 東洋ゴム工業株式会社 空気タイヤとリムの組立体
SE7703619L (sv) 1976-04-03 1977-10-04 Dunlop Ltd Pneumatiskt deck- hjulfelgaggregat
JPS53138106A (en) 1976-10-02 1978-12-02 Toyo Tire & Rubber Co Ltd Pneumatic safety tire
JP3983357B2 (ja) * 1997-11-28 2007-09-26 株式会社ブリヂストン 空気入りタイヤ
JP4015286B2 (ja) * 1998-06-22 2007-11-28 住友ゴム工業株式会社 空気入りタイヤ
JP2004168201A (ja) * 2002-11-20 2004-06-17 Sumitomo Rubber Ind Ltd 空気入りタイヤ
JP4172995B2 (ja) * 2002-12-02 2008-10-29 株式会社ブリヂストン ランフラットラジアルタイヤ
JP4289543B2 (ja) * 2003-03-18 2009-07-01 東洋ゴム工業株式会社 ランフラットタイヤ

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US7562685B2 (en) 2009-07-21
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US20070209745A1 (en) 2007-09-13
EP1808314A4 (de) 2008-11-26

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